Annealing furnace



April 27, 1926. 1,582,036

H. GRUNEWALD ANNEALING FURNACE Filed Feb. '7, 1925 2 Sheets-Sheet 1 April 27 1926. 1,582,036

H. GRUNEWALD ANNEALING FURNACE Filed Feb '7, 1925 2 sheets-Sheet 2 Patented/Apr. 27, 1926,

UNITED STATES PATENT OFF-ICE.

ANNEALTNG FURNACE.

Application filed February 7, 1925. Serial No. 7,626.

To all whom it may concern:

Be it known that I, HEINRICH Gni'mn WALD, a citizen of the Republic of Germany, residing at Hilchenbach, \Vestphalia, Germany, have invented new and useful Improvements in Annealing Furnaces, of which the following is a specification.

My invention relates to annealing furnaces and more particularly to furnaces for removing scale, oxide, etc.,-from hoop iron,

' "wire, plate and other metal objects.

Such articles were heretofore generally treated in pots the cavities of which were filled with gray cast iron chip's. This method is expensive and involves loss of time due to the frequent filling and refilling of the pots. i

It has been proposed to improve this method by performing it in an atmosphere 0 separate from the atmosphericair or in an inert gas. Such furnaces, however, are com plieated, -involve high initial cost and the danger of explosion in case of failure" of their complicated mechanism.

I have found that it is possible to remove scale, etc., from commercial iron, hoop iron, wire, plate and all other metals without in-- sert-ing chipsof gray cast iron or introducing inert gas. It is sufiicientto close the furnace air-tight and to heat it to the desired top ofthe furnace. V Retorts adapted to receive the charge or temperature at which it is kept for the time required.

order'to enable the closure to exclude air with reliability during the functioning of the furnace, itshould be remote from'the' heated zone. This is effected according to my invention by arranging the closure for the vessels containing the charge, which may be the retorts or a pot inserted therein, atthe' the pots extend to the upper end of the 'furnace. where they cover. The brick torts in its upper portion and per end ofthe furnace. By this arrangement, excessive heating of below the up;

the cover and deterioration of the closure is prevented Without interfering lwith the drauht. i

It as beenfound that thetemperature of .the cover is 200'to 300 centrigrade'so. that there is no danger ofdamage to the closure. n

on a circular track at its perimeter,

to enable it to be are closed by a gas-tight WOrk tightly hugs the re- 1 the retort and to utilize the heat of the fur-. nace properly, the annealing chamber and the. retort are secured -to a movable plate which is carried on a pillar at its centre and sure on the track being distributed by rollers. The circular track at the same time serves to close the furnace. In this manner,.the annealing' chamber which comprises the flues for the furnace gases, is made movable together with the retort. The heat of. the

gases isutilized to the full extent, the gases flowing through each of the annealing chambers in the prescribed direction and giving up their heat. During the heating of the retorts, the fur nace should be in the most favourable position with regard to them and secondary air passages, etc, should be avoided. To this end, the furnacechamber is adapted to be adjusted horizontally adapted to-the existing conditions of operation. During the heating period, the furnacechamber is adjacent the ase of the annealing chamber-so as to provide a single combustion and flue chamber in which the heat of the gases is fully utilized.

Reference is to'be had/to the accompany- 'ing drawings in which my improved furnace is illustrated byway of p Fig. 1 is a longitudinal sectionlofa "furnac-e equipped with a I furnace chamber-.

example.

adapted 'to be raised and lowered,

Fig. 2 is aplan view of the furnace' Arotatable cover plate a is supported on a l the presand vertically so as pillar 0 by' a -thrust-ball bearing 6 at centre; Its perimeter is carried-onrollers'e running on a circular track (Z, said rollersbeing kept apart by a cage 7. V The cage en,-

gages grooves g'and .g" of the-track and cover plate c, res'pectively,' and serves for preventing loss of heat from the annealing chamber flue h.

The cover plate a with the annealing chambers, the retorts and annealing pots, may be rotated by any suitable means, not shown.

The annealing chambers are suspended from the plate a and the retorts 7c are secured in suitable holes in the plate a.

The retorts k which may be of any suitable shape, of circular or rectangular section, as required by the goods to be treated, are equipped with pots Z in which the charge is placed on a table m to facilitate inserting and withdrawing. The pot Z is closed at the top by a cover or. To prevent heating of the sealing faces, a passage 0 may be formed in the cover 11. in which cooling water is circulated.

Two tubes p and g are secured in each cover n, the tube p being closed at the bottom and open at the top and serving for inserting a pyrometer so that the temperature of the charge can be measured without allowing air toenter the pot Z. The tube (1 which is open at both ends is equipped with a safety valve, not shown, in order to allow vapours of oil or steam to escape which may form from grease or moisture adhering to the goods.

The operation of the furnace is as follows: Suppose all four chambers 1, 2, 3 and 4 as shown in the plan view, to be charged. That chamber which is above the furnace r-or a gas or oil burner, as the case may be, is heated until the desired temperature, say 770 to 800 centigrade, has been attained. Now, the furnace chamber a is lowered by any suitable means, for instance ascrew u, a bevel gear t, a shaft 8 and a handwheel 'v, or the gas or oil burner not shown, is withdrawn so as to enable the chamber 21 to be revolved with the cover plate at until the next chamber is above the furnace chamber T which is now raised until its flange w engages a corresponding flange m at the bottom of the chamber 2'. gas-fired furnace, the burner is replaced. The chamber 11 which is now above the furnace 1- has been previously heated to 500 to 600 centigrade by the waste gases from the furnace which circulate around those chambers, for instance 2, 3, and 4, which are not being heated by the furnace chamber 1", or the burner at the time. \To this end, the chambers 21 are connected by flues y, 3 1 and y and that chamber which is opposite the chamber being heated, in the present instance 3, is connected to a flue z in the brickwork of the furnace which conducts the waste gases to a chimney, not shown.

The chamber 71 is now heated to the desired temperature and maintained at that for 1 to 2 hours, whereupon the plate a is again rotated so as to place the chamber 3 above the furnace-which has been previously lowered by the means describedor the burner. The chamber 1 is now in the In the case of an oil or original position of the chamber 3. The pot Z of this chamber with the annealed and partly cooled charge is now withdrawn and replaced for a fresh pot. The position of chamber 3 in the plan view is the station where the pots are exchanged. The operation is now repeated.

In my novel furnace, I may anneal 1000 to 1500 kilogrammes of goods during a period of one hour or two hours.

Instead of revolving annealing chambers. chambers adapted to move on a straight line may be provided. This arrangement is very suitable for plate annealing furnaces in which the goods are charged in boxshaped pots which may be suspended from a track on top of the passage. By these means, it is possible to close the passage and the boxes perfectly tightly from above. The plates are annealed bright for their entire. area which was not practicable heretofore as the rims of the plates colouredblue on a strip 4 in. wide, or more which is very inconvenient with regard to galvanizing and lacquering the plates.

The gases from the furnace chamber 7' or the burner flow upwards along the chamber 1' which is above the furnace, being the chamber 1 in the present instance, to the chamber 2 through the flue 3 along that chamber in downward direction, through the flue 1 to the chamber 3, along that chamber in upward direction, and to the chimney flue z. Dampers or slides 11 y, 3 3 and z, are provided in the respective flues. The chambers are cooled at the station where the chamber 4 is shown. The heat radiated from this chamber is conducted to the flue a through the flue y and along the chamber 3. In this manner the radiating heat is utilized and, together with the waste gases, heats the goods to 300 or 400 centi ade.

In a urnace having 6 or 8 annealing chambers instead of four, as shown, it is possible to completely cool the goods in the furnace. Pots may be dispensed with in this manner, the tables m with the charge being inserted directly in the retorts and treated as described.

1 claim:

.1. In an annealing furnace, in 'combinaticn, anannealing chamber, a masonry linirig in said chamber, a cover for the chamber and the lining, a flanged retort arranged through the cover and supported thereby and positioned in spaced relation to the lining of the chamber and snugly engaged only adjacent its top by the lining to avoid unnecessary heating, and an adjustable gas tight cover for the retort positioned above the cover for the chamber.

9.. In an annealing furnace, in combination, a rotary plate supported at the top of 130 said furnace, annealing chambers secured t% said plate, means for heating said chambers, and covers secured to said chambers at the top of said furnace.

3. In an annealing furnace, in combinat1on, a rotary plate supported at the top of said furnace, annealing chambers secured to said plate, means for heating said chambers, covers secured to said chambers at the top of said furnace, a pillar in said furnace adapted to support said plate at the centre, and a circular track in said furnace adaptcd to support said plate at its perimeter.

I. In an annealing furnace, in combination, a rotary plate supported at the top of said furnace, annealing chambers secured to said plate, means for heating said chambers, covers secured to said chambers at the top of said furnace, a pillar in said furnace adapted to support said plate at the centre, a circular track adapted to support said plate at its perimeter, and a ring adapted to make gas-tight; connection between said plate and said track.

5. In an annealing furnace as claimed in claim 1',whercin an insert tank is provided at its upper edge with a flange for engagement with the flanged retort when the tank is arranged within the retort, and the adjustable cover extending partially into the interior of the tank and provided with an external annular flange for engagement with the flange on the tank to act as a. gas tight closure for said tank. 7

6. In an annealing furnace as claimed in claim 1, wherein a tank is arranged within said retort and supported on the annealing chamber cover, a metal supporting table arranged in the bottom of the furnace and the adjustable cover acting to secure the tank in position and to also extend partly within the tank to act as a gas tight closure therefor, a safety valve carrying pipe arranged through the adjustable cover and opening interiorly of the tank to permit of the escape of gases formed during the heating, and another pipe arranged through the adjustable cover and having the inner part closed and the outer part opened, and a pyrometer. engaged in the outer open end of the last mentioned pipe.

7. In an annealing furnace, in combina- HEINRICH GRUNEWALD.

'tion, an annealing chamber, a cover secured 

